*

Portfolio securities and other financial instruments for which market quotations are readily available are stated at market value. Market value is generally determined on the basis of last reported sales prices, or if no sales are reported, on the basis of quotes obtained from a quotation reporting system, established market makers, or independent pricing services.

Portfolio securities and other financial instruments for which market quotations are not readily available, or for which a development/event occurs that may significantly impact the value of a security, are fair-valued, in good faith, pursuant to procedures established by the Board of Trustees, or persons acting at their discretion pursuant to procedures established by the Board of Trustees. The Fund’s investments are valued daily using prices supplied by an independent pricing service or dealer quotations, or by using the last sale price on the exchange that is the primary market for such securities, or the mean between the last quoted bid and ask price. Independent pricing services use information provided by market makers or estimates of market values obtained from yield data relating to investments or securities with similar characteristics. Short term securities maturing in 60 days or less are valued at amortized cost, if their original term to maturity was 60 days or less, or by amortizing their value on the 61st day prior to maturity, if the original term to maturity exceeded 60 days.

The prices used by the Fund to value securities may differ from the value that would be realized if the securities were sold and these differences could be material. The Fund’s net asset value is normally determined as of the close of regular trading (normally, 4:00 p.m. Eastern time) on the New York Stock Exchange (“NYSE”) on each day the NYSE is open for business.

(a)

Private Placement—Restricted as to resale and may not have a readily available market. Securities with an aggregate value of $25,732,978, representing 5.9% of total investments.

(b)

Illiquid.

(c)

144A—Exempt from registration under Rule 144A of the Securities Act of 1933. These securities may be resold in transactions exempt from registration, typically only to qualified institutional buyers. Unless otherwise indicated, these securities are not considered to be illiquid.

(d)

Inverse Floater—The interest rate shown bears an inverse relationship to the interest rate on another security or the value of an index. The interest rate disclosed reflects the rate in effect on February 28, 2011.

(e)

Variable Rate Notes—Instruments whose interest rates change on specified date (such as a coupon date or interest payment date) and/or whose interest rates vary with changes in a designated base rate (such as the prime interest rate). The interest rate disclosed reflects the rate in effect on February 28, 2011.

(f)

All or partial amount segregated for the benefit of the counterparty as collateral for reverse repurchase agreements.

(g)

Residual Interest Bonds held in Trust—Securities represent underlying bonds transferred to a separate securitization trust established in a tender option bond transaction in which the Fund acquired the residual interest certificates. These securities serve as collateral in a financing transaction.

(h)

Step Bond—Coupon is a fixed rate for an initial period then resets at a specific date and rate.

(i)

Restricted. The aggregate acquisition cost of such securities is $4,045,753 and the aggregate market value is $3,390,303, representing 0.8% of total investments.

(j)

All or partial amount segregated for the benefit of the counterparty as collateral for derivatives.

(k)

Rates reflect the effective yields at purchase date.

(l)

At February 28, 2011, the cost basis of investments for federal income tax purposes was $389,060,894. Aggregate gross unrealized appreciation for securities in which there was an excess value over tax cost was $13,463,232; aggregate gross unrealized depreciation for securities in which there was an excess of tax cost over value was $16,317,622; and net unrealized depreciation for federal income tax purposes was $2,854,390. The difference between book and tax cost was attributable to inverse floater transactions.

Glossary:

AGC — insured by Assured Guaranty Corp.

AGM — insured by Assured Guaranty Municipal Corp.

AMBAC — insured by American Municipal Bond Assurance Corp.

CA St. Mtg. — insured by California State Mortgage

CP — Certificates of Participation

FGIC — insured by Financial Guaranty Insurance Co.

FHA — insured by Federal Housing Administration

GO — General Obligation Bond

GTD — Guaranteed

IBC — Insurance Bond Certificate

NPFGC — insured by National Public Finance Guarantee Corp.

NR — Not Rated

TCRS — Temporary Custodian Receipts

WR — Withdrawn Rating

Rate Type

Upfront

Swap Counterparty

Notional Amount
(000s)

Termination
Date

Payments
Made

Payments
Received

Market
Value

Premiums
Paid (Received)

Unrealized
Depreciation

Bank of America

$34,000

6/20/42

(4.75

)%

3-Month USD-LIBOR

$  (942,229

)

$(321,550

)

$  (620,679

)

Citigroup

13,900

6/20/42

(4.75

)%

3-Month USD-LIBOR

(385,205

)

(236,300

)

(148,905

)

Goldman Sachs

8,200

6/20/42

(4.75

)%

3-Month USD-LIBOR

(227,243

)

64,780

(292,023

)

Morgan Stanley

9,600

6/20/42

(4.75

)%

3-Month USD-LIBOR

(266,041

)

153,600

(419,641

)

$(1,820,718

)

$(339,470

)

$(1,481,248

)

LIBOR - London Inter-Bank Offered Rate

Counterparty

Rate

Trade Date

Maturity Date

Principal & Interest

Principal

Credit Suisse First Boston

0.65

%

2/17/11

3/17/11

$3,282,711

$3,282,000